Drive unit equipped with electrical motor

ABSTRACT

A drive unit equipped with an electric motor including an input shaft that is connected to an engine, an electric motor shaft, a counter output shaft, and a planetary gear set, wherein the input shaft and the counter output shaft are connected respectively, on one side of the planetary gear set, to two other elements which are different from an element with which the electric motor shaft is connected, an outer circumference of both edge portions of the counter output shaft is supported by a drive unit case, and an outer circumference of the input shaft is supported by an inner circumference of the counter output shaft by the drive unit case through the counter output shaft.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a drive unit for a vehicle equipped with anelectric motor.

2. Description of Related Art

A drive unit for an electric vehicle or a hybrid drive unit has beenadopted as a drive unit for a vehicle, in which an electric motor isused as a drive source. A similar drive unit has been disclosed inJapanese Patent Laid-Open No. 2001-187535, in which an engine, agenerator, and a gear train, which is drive-connected to a wheel througha differential unit, are connected through a planetary gear set. Powercan thus mutually transmit among the engine, the generator, and thewheel. Accordingly, the drive unit can freely execute driving of thegenerator by the engine, assist in the driving force and start theengine when the generator serves as the electric motor, and performregeneration using an inertia power which is returned from the wheel tothe planetary gear set through the differential unit.

In the aforementioned conventional art, the engine and the generator arealigned coaxially in a side-by-side manner with the planetary gear setcoaxially interposed therebetween. Furthermore, the gear train has adual shaft structure with an input shaft for connecting the engine withone element of the planetary gear set, and a counter output shaft forconnecting the wheel with the other elements of the planetary gear setthrough the gear train and the differential unit. The input shaft andthe output shaft are related in which the input shaft serves as an innercircumference and the output shaft serves as an outer circumference.

SUMMARY OF THE INVENTION

In the conventional art, however, a counter drive gear (21) for engineoutput (hereinafter, for the purpose of reference, the names or thereference numerals, otherwise both, of the members in the disclosedJapanese Patent Laid-Open No. 2001-187535 will be denoted withparentheses) is supported on one side by a pair of bearings (angularcontact ball bearings 53, 53), on a case supporting wall (40a).

This kind of one-sided supporting structure does not cause problems inthat the supporting wall has sufficient rigidity strength. However, whenthe driving unit is provided with a generator, a power supply cablehaving a large wire diameter for connecting the generator and a controlunit has to be guided from the outside of the drive unit case into theinside thereof so as to be connected with a stator coil of thegenerator. This causes a problem. Particularly, as in the conventionalart which has a structure in which an electric control unit (104) suchas an inverter is integrated with the drive unit, an introductionportion of a cable (wiring 100c) should be provided at a place otherthan a control unit mounting portion. Furthermore, if the introductionportion is provided with space for a cable connection, it is unavoidablethat the portion corresponds to an outside circumferential side of theplanetary gear set (planetary gear 6) which has a small outer diameter.A large window hole is thus used for cable connection work that must beprovided on the supporting wall of the counter drive gear (21).Accordingly, rigidity strength of the supporting wall is unavoidablydecreased due to the formation of this window hole. In suchcircumstances, in the aforementioned one-side-supporting structure, anoscillated rotation of the counter drive gear still easily occurs, andthus gear noise occurs due to a meshing misalignment with the counterdriven gear.

In addition, with regard to an input shaft (13) which is supported by acounter output shaft (a running rotation shaft 16), a coupling portionside thereof with respect to the planetary gear set is supported by thecounter output shaft through a needle bearing (57). In this supportingstructure, the input shaft is supported by the case supporting wall(40a) through the counter output shaft, a boss portion (21a) of thecounter drive gear (21), and the ball bearings (53,53). In thissupporting structure, the input shaft is influenced by the oscillatedrotation of the counter drive gear (21). Furthermore, the needle bearing(57) is arranged in a misaligned axial direction with respect to aspline-engaging portion of the counter drive gear (21) and the counteroutput shaft. A slightly oscillated rotation of the counter drive gear(21) is thus amplified in a supporting portion of the input shaft (13)to the counter output shaft. This, combined with the aforementionedinfluence, results in more unstable supporting of the input shaft 13.This factor can thus cause a meshing misalignment among a sun gear, apinion gear and a ring gear of the planetary gear set.

Hence, the invention thus provides a drive unit equipped with anelectric motor, in which a counter output shaft is stably supported, theoscillated rotation of the counter drive gear is inhibited, and gearnoise due to meshing misalignment with a counter driven gear can beprevented. Furthermore, the invention also prevents meshing misalignmentof the planetary gear set which is arranged on the same shaft as thecounter output shaft.

To achieve the foregoing as well as other advantages, the invention isprovided with a drive unit equipped with an electric motor, including aninput shaft that is connected to an engine, an electric motor shaft thatserves as an output shaft of an electric motor, a counter output shaft,and a planetary gear set for drive-connecting the input shaft, theelectric motor shaft and the counter output shaft so as to enable mutualtransmission of power in which the input shaft is arranged in a coaxialrelationship in an inner circumference of the counter output shaft,wherein the input shaft and the counter output shaft are connectedrespectively, on one side of the planetary gear set, to two otherelements which are different from an element with which the electricmotor shaft is connected, an outer circumference of both edge portionsof the counter output shaft is supported by a drive unit case, and anouter circumference of the input shaft is supported by an innercircumference of the counter output shaft by the drive unit case throughthe counter output shaft.

In this structure, the counter output shaft is supported at both endportions thereof by the drive unit case, and thus an inclination of thecounter output shaft due to a torque-transmission load is inhibited.Accordingly, an oscillated rotation of the counter output shaft isprevented, thereby gear misalignment due to the oscillated rotation isprevented, and gear noise occurrence is therefore prevented.Furthermore, the input shaft is supported by the drive unit case throughthe counter output shaft for which the oscillated rotation has beeninhibited, and thus the oscillated rotation of the input shaft is alsoprevented. Therefore, misalignment of the planetary gear set connectedthereto is also prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will be described with reference tothe figures, wherein:

FIG. 1 is a partial sectional view of a hybrid drive unit in an axialdirection, according to an embodiment of the invention;

FIG. 2 is a skeleton view of a gear train of the hybrid drive unit;

FIG. 3 is a developed cross-sectional view of the hybrid drive unit inthe axial direction, developed along a gear train; and

FIG. 4 is a side elevational view of the hybrid drive unit viewed froman engine connection side, in which a front cover of a case has beenremoved.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment of the invention will be described with reference to thefigures. First, FIG. 2 is a skeleton view schematically showing a hybriddrive unit in which the invention is adopted. In this figure, a geartrain is developed on a same plane. This unit is provided as a driveunit of a transversely placement type, in which an engine E, an electricmotor (motor) 2, and a differential unit 3 are arranged parallel ondifferent axial lines respectively. Hereinafter, these axial lines arereferred to as an engine axial line X, an electric motor axial line Y,and a differential axial line Z, in the description of the embodiment.Furthermore, a generator 4 is disposed on the engine axial line X, and agear train 5 is disposed for drive-connecting the engine E, the motor 2,and the generator 4 to the differential unit 3 on parallel axes. Acounter shaft 50 of the gear train 5 is arranged on another axial line(similarly, referred to as a counter axial line U) different from therespective axial lines mentioned above. Further, a planetary gear set 6is arranged on the engine axial line X for drive-connecting the engineE, the generator 4, and a counter drive gear 51 of the gear train 5, ina differential relationship. In addition, a one-way clutch 7 is arrangedon the engine axial line X for preventing a reverse rotation of theengine E for the purpose to be described later. Furthermore, a brakingunit 8 for appropriately stopping a rotation of the generator 4 isarranged.

A specific drive-connecting relationship of the elements on theaforementioned respective axial lines in this drive unit are providedsuch that an input shaft 11 on the engine axial line X is connected at arear edge thereof (hereinafter, a front-rear relationship of therespective shafts described assuming that the side on which the engineis placed is the front), to a carrier 61 of the planetary gear set 6; anelectric motor shaft 41 which is provided with a rotor shaft of thegenerator 4 is connected at a front edge thereof to a sun gear 62 of theplanetary gear set 6, and in addition, connected at a rear edge thereofto a drive unit case 9 through the braking unit 8; and a ring gear 63 ofthe planetary gear set 6 is connected to a rear edge of a counter outputshaft 12 which is integrated with the counter drive gear 51 constitutingan output member on the engine axial line X. An output element on themotor axial line Y is provided as a counter drive gear 52 which isconnected to a front edge of a rotor shaft 21 of the motor 2. Both ofthese counter drive gears 51, 52 are meshed with counter driven gears53, 54 arranged on the counter axial line U, thereby beingdrive-connected to the counter shaft 50. The counter shaft 50 isdrive-connected to the differential unit 3 such that a differentialdrive pinion gear 55 which is arranged in a rear edge thereof on theaxial line U is meshed with a differential ring gear 31 which is fixedto a differential case 30 of the differential unit 3. Further, theone-way clutch 7 is connected to a rear edge of the carrier 61 of theplanetary gear set 6 and to the drive unit case 9, thereby beingarranged between the planetary gear set 6 and the generator 4.Additionally, the braking unit 8 is connected to a rear edge of therotor shaft 41 of the generator 4. Note that a reference alpha-numeral Win the figure shows a wheel which is drive-connected to a side gear (notshown) in the differential unit 3.

FIG. 3 is a developed sectional view in the axial direction and FIG. 4is a side elevational view, respectively, showing the structure of thedrive unit in detail. To describe the detail structure which cannot beshown in the foregoing FIG. 2, referring to FIG. 3, the motor 2 and thegenerator 4, the gear train 5, and the differential unit 3 are housed inthe drive unit case 9. The drive unit case 9 has an intermediate wall 91on a front side of the case body 90 thereof, and has openings in frontand rear edges thereof. The drive unit case 9 is further provided with afront cover 92 which serves as a front wall for covering these openings,and with a rear cover 93 which serves as a rear wall. In addition, aspace provided between the intermediate wall 91 of the case body 90 andthe rear cover 93 serves as a housing portion for the motor 2, thegenerator 4, and the planetary gear set 6. A space provided between theintermediate wall 91 of the case body 90 and the front cover 92 servesas the housing portion for the gear train 5 and the differential unit 3.

The motor 2 is arranged in the motor housing space such that a stator ofthe motor 2 is provided so as that the stator does not rotate on aperipheral wall of the case body 90. The rotor shaft 21 is supported bythe front and rear edges thereof respectively on the intermediate wall91 and the rear cover 93 through a radial ball bearing. A gear shaft 22is connected to the front edge of the rotor shaft 21 byspline-engagement. The front and rear edges of the gear shaft 22 aresupported by the front cover 92 and by the intermediate wall 91respectively through the radial ball bearing. Further, the counter drivegear 52 is integrally formed in this gear shaft 22.

The generator 4 is arranged in the generator housing space such that thestator thereof does not rotate on the peripheral wall of the case body90. The rotor shaft 41 thereof is provided such that an intermediateportion thereof is supported by a wall of the housing portion for theplanetary gear set 6, which is provided as an ancillary on theintermediate wall 91, and such that the rear edge thereof is supportedby the rear cover 93, respectively through the radial ball bearings. Thesun gear 62 of the planetary gear set 6 is connected byspline-engagement to a portion closer to a front edge of the rotor shaft21. A tip portion of the rotor shaft 41 is fitted into a rear edge ofthe input shaft 11 in an oil-tight state.

The differential unit 3 is arranged in the housing portion therefore,with the front and rear edges of the differential case 30 beingsupported on the front cover 92 and the intermediate wall 91respectively, through tapered roller bearings.

The counter shaft 50 of the gear train 5 is arranged in a respectivehousing portion, with the front and rear edges thereof being supportedon the front cover 92 and the intermediate wall 91 respectively, throughthe tapered roller bearings. A differential drive pinion gear 55 isintegrally formed on a rear half portion of the counter shaft 50. In afront half portion, the counter driven gear 54 is fitted byspline-engagement in order to prevent rotation. In addition, the counterdriven gear 53 is fixed by a bolt on a rear side of the counter drivengear 54.

An actual positional relationship of each of the axial lines X, Y, Z, Uis shown in FIG. 4. In this drive unit, the differential axial line Z isarranged on a lowest portion of the unit, and the engine axial line X isarranged in a diagonal upper portion therefrom (a front portion whenbeing mounted in a vehicle). The motor axial line Y is arranged in anupper portion of the differential axial line Z. The counter axial line Uis arranged in an intermediate portion of the aforementioned three axiallines X, Y, Z. In addition, the motor 2 and the generator 4, andfurthermore, a control unit C including therein an inverter and anelectronic control unit for controlling the braking unit 8 areexternally mounted on the drive unit case 9. A mounting position thereofis such that a plane substantially in contact with the outercircumferences of the motor 2 and the generator 4 is provided as analignment face of case frames of the drive unit case 9 and the controlunit C. As mentioned above, since the engine axial line X and the motoraxial line Y are different in height, this alignment face is inclinedforward and downward toward a front portion (the right hand side in FIG.4) of a vehicle in a state where the drive unit is mounted.

Electric power supply cables 20, 40 in groups of three are arranged sideby side in a longitudinal direction of the control unit C, that is, in afront-rear direction thereof when the electric power supply cables 20,40 are mounted on a vehicle. These cables are introduced into a geartrain housing space in the drive unit case 9, from a plane alignmentface of the drive unit case 9 and the control unit C. Then, each of theterminals are connected to a winding cable terminal which is guided outfrom a winding of the motor and the generator through a window hole inthe intermediate wall. Therefore, a connection portion of theseterminals is placed, in the axial direction, at a position between themotor 2 and the counter drive gear 52 thereof, in the gear train housingspace, the position being the same as a position at which the planetarygear set is disposed.

As shown in detail in an enlarged view in FIG. 1, in accordance with afeature of the invention, the input shaft 11 and the counter outputshaft 12 are respectively connected to the carrier 61 and the ring gear63 which serve as two other elements different from an element to whichthe rotor shaft 41 as an electric motor shaft is connected, that is, thesun gear 62, is connected on the other side of the planetary gear set 6.The counter output shaft 12 has a counter drive gear 51 integratedtherewith, and is provided such that the outer circumferences of bothedge portions thereof (rigorously, the front edge and the rear edgeexcluding tips which serve as connection portions to the crank shaft 10of the engine) are supported by the front cover 92 and the intermediatewall 91 of the drive unit case 9, through the radial ball bearings 56,57. The input shaft 11 is supported by the drive unit case 9 through thecounter output shaft 12 such that the outer circumference of the inputshaft 11 is both-side-supported by the counter output shaft 12 throughone pair of needle bearings on an inner circumferential side of thesupporting portion to the drive unit case 9 of the counter output shaft12. A tip of this input shaft 11 is connected to the crank shaft 10 ofthe engine through a unit 13 having a torque limitter, which serves as aflywheel and as a damper. As apparent from each connection relationshipdescribed above, the counter output shaft 12 is connected to the wheel Wthrough the gear train 5 which is provided with the counter drive gear51, the same driven gear 53, the counter shaft 50, the differentialdrive pinion gear 55, and the differential ring gear 31. Therelationship is provided such that the motor 2 which serves as a secondelectric motor is connected to the counter shaft 50 in this gear train 5through the counter drive gear 51 and the driven gear 54.

In the planetary gear set 6, the carrier 61 which serves as an elementconnected to the input shaft 11 is arranged in the rear side of theintermediate wall 91 such that the rear edge of the input shaft 11 isprovided as a carrier flange, and furthermore, such that the carriercover is drive-connected, on the other side of the planetary gear set 6,to an oil pump P of which a pump body is embedded in the intermediatewall. In further detail, the connection to the rotor shaft is providedsuch that a meshing with a ring-shaped spur gear 58, fixed to thecarrier cover, is made. The connection by the ring-shaped spur gear 58being made through a spur gear 59 fixed to the rotor shaft of the oilpump P. Furthermore, the front side of the ring gear 63 is connected byspline-engagement to the rear edge of the counter output shaft 12through the ring gear flange.

The one-way clutch 7 is supported such that an inner lace thereof isconnected to the carrier 61 of the planetary gear set 6, and that anouter lace is fitted by spline into a wall of the planetary gear sethousing portion.

The braking unit 8 is structured such that the rotor 42 side of thegenerator 4 is provided as a drum, and that a boss portion protrudingfrom the rear cover 93 of the drive unit case 9 serves as a hub. Thebraking unit 8 is also structured from a friction material disc 82 and aseparator plate 83 which are provided as friction engagement members,and that an oil servo for engaging/disengaging the friction engagingmembers is assembled in the rear cover 93. The friction material disc 82is provided such that an inner circumference of a circular flangeportion overhanging from an edge plate of the rotor 42 in the axialdirection is engaged by a spline with an outer circumference thereof.The separator plate 83 is provided such that an outer circumference ofthe hub is engaged by a spline with an inner circumference thereof.

In the drive unit having this structure, referring to FIG. 2, the motor2 and the wheel W are related so as to be directly connected through thegear train 5 for power transmission, separately from a differentialrotation by the differential unit 3. On the other hand, the engine E andthe generator 4 are connected to the gear train 5 in a differentialrelationship through the planetary gear set 6 for power transmission.Accordingly, the engine E, the generator 4, and the motor 2 areappropriately controlled in order to drive the wheel shaft W with amotor output only, with an engine output only, or with the engine outputassisted by the motor output. The vehicle is thus allowed to run using abattery recharged by the generator 4 driven by the engine E output inaccordance with a remaining amount of a battery and with a running load.

During the driving operation control described above, the rotor shaft 41of the generator 4 is latched with the drive unit case 9 as required.The braking unit 8 thus functions to prevent a driving loss generationby being rotated by a reaction torque when electric power generation isnot required. Furthermore in this drive unit, the generator 4 is drivenas the motor, and thus a reaction force applied to the carrier 61 of theplanetary gear set 6 is reversely rotated. Accordingly, the reactionforce element is provided through the one-way clutch 7, for engaging thecarrier 61 with the drive unit case 9. Therefore, an output from thegenerator 4 can be transmitted to the ring gear 63, and the power can beincreased (parallel mode running) when the vehicle is started by aco-output of the motor 2 and the generator 4.

As described above in detail, in the drive unit according to thisembodiment, the counter output shaft 12 is both-side-supported by bothside portions thereof, by the drive unit case 9. Accordingly,inclination due to the reaction force in meshing the counter driven gear52 with the counter drive gear 51 integrated with the counter outputshaft 12 is inhibited. Therefore, oscillated rotation of the counteroutput shaft 12 is prevented, thereby meshing misalignment of the gears51 and 52 due to the oscillated rotation is eliminated, and thus gearnoise occurrence is prevented. Additionally, the input shaft 11 is alsosupported by the drive unit case 9 through the counter output shaft 12in which oscillated rotation has been inhibited, and thereforeoscillated rotation of the input shaft 11 is also prevented.Consequently, the planetary gear set 6 which is connected thereto isalso prevented from engaging in a misalignment manner. Furthermore, theinput shaft 11 is supported by the same counter output shaft 12, therebythe supporting accuracy of the input shaft 11 on the drive unit case 9is improved. In addition, both side-supporting portions of the inputshaft 11 is placed at the same position, in the axial direction, as theboth-side-supporting portions of the counter output shaft 12. Therefore,the supporting accuracy of the input shaft 11 is not influenced by theflexure of the counter output shaft 12.

Further, the supporting load on the counter output shaft 12 can bedistributed to the case body 90 and to the front cover 92 thereof, andthus the load applied to the case body 90, for which it is difficult tokeep the rigidity strength due to the formation of the window hole forconnecting the cables 20, 40, can be reduced compared with aconventional structure in which the case body 90 provides a one-sidesupporting. Furthermore, combined with the distribution of thesupporting load, the radial ball bearings 56, 57 are provided as thesupporting mechanism. Accordingly, work hours for assembling the counteroutput shaft can be reduced because the necessity for fasteningadjustment of the bearing is eliminated, and the cost and size of thebearing can be reduced.

Furthermore, the outer diameter of the input shaft 11 is automaticallydetermined by an amount of an input torque while the counter outputshaft 12 and the counter drive gear 51 are integrated and thus the outerdiameter of the counter drive gear 51 can be decreased while the torquetransmission strength is maintained. Therefore, the counter gear ratiocan be given more freely. Furthermore, the supporting accuracy of thecounter drive gear 51 equals the supporting accuracy of the counteroutput shaft 12, and thus the supporting accuracy of the input shaft 11which is supported by the counter output shaft 12 is improved, and ameshing accuracy of the planetary gear set 6 is also improved.

Additionally, the drive mechanism of the oil pump P can be arrangedcloser to the generator 4 than the both of the supporting portions ofthe counter output shaft 12, with the planetary gear set 6 interposed.Therefore, the oil pump P also can be disposed on the electric motorhousing portion side of the drive unit case 9. Therefore, the oilpassage can be arranged using the case wall which surrounds the electricmotor housing portion.

In the invention, in accordance with an embodiment thereof, it ispossible for the supporting accuracy of the input shaft to be unaffectedby a flexure of the counter output shaft.

According to another embodiment of the invention, the input shaft isboth side-supported by the same counter output shaft, and thus thesupporting accuracy of the input shaft on the drive unit case isimproved. Furthermore, the both side-supporting portion of the inputshaft is placed at the same position as the both side-supporting portionof the counter output shaft, in the axial direction. Accordingly, thesupporting accuracy of the input shaft is not influenced by the flexureof the counter output shaft.

According to another embodiment of the invention, a supporting load onthe counter output shaft can be distributed to the case body and thefront cover thereof. Accordingly, compared with a conventional structurein which one side-supporting on the case body is made, it is possible toreduce the load on the case body for which the rigidity strength isdifficult to be maintained because a window hole for cable connection isformed. In addition to the distribution of the supporting load, if theradial ball bearing is provided as a supporting mechanism, it ispossible to decrease work hours for assembling the counter output shaftbecause the bearing fastening adjustment is not necessary, anddownsizing of the bearing and cost reduction are possible.

According to another embodiment of the invention, the outer diameter ofthe input shaft is automatically determined by an amount of an inputtorque while the counter output shaft and the counter drive gear areintegrated and thus the outer diameter of the counter drive gear can bedecreased while the torque transmission strength is maintained.Therefore, the counter gear ratio can be given more freely. Therefore,the supporting accuracy of the input shaft supported on the counteroutput shaft is improved, and the meshing accuracy of the planetary gearset is also improved.

According to another embodiment of the invention, with the planetarygear set interposed, a drive mechanism of the oil pump can be arrangedcloser to the electric motor than the both side-supporting portion ofthe counter output shaft, and thus the oil pump also can be disposed onthe electric motor housing portion side of the drive unit case.Therefore, an oil passage can be arranged using a case wall whichsurrounds an electric motor housing portion.

According to another embodiment of the invention, each effect mentionedabove can be achieved for a hybrid drive unit in which two electricmotors are arranged.

The invention was described hereinabove in detail, according to theembodiment in which the invention is adopted solely for a hybrid driveunit. However, the invention is not limited to this embodiment, butinstead, may be carried out by variously modifying within the scope ofthe invention.

1. A drive unit equipped with an electric motor, comprising: an inputshaft that is connected to an engine; an electric motor shaft thatserves as an output shaft of an electric motor; a counter output shaft;and a planetary gear set for drive-connecting the input shaft, theelectric motor shaft and the counter output shaft so as to enable mutualtransmission of power in which the input shaft is arranged in a coaxialrelationship in an inner circumference of the counter output shaft,wherein the input shaft and the counter output shaft are connectedrespectively, on one side of the planetary gear set, to two otherelements which are different from an element with which the electricmotor shaft is connected, an outer circumference of both edge portionsof the counter output shaft is supported by a drive unit case, and anouter circumference of the input shaft is supported by an innercircumference of the counter output shaft; by the drive unit casethrough the counter output shaft.
 2. The drive unit equipped with theelectric motor according to claim 1, wherein a supporting portion of theinput shaft is placed at a same position as a supporting portion of thecounter output shaft, in an axial direction.
 3. The drive unit equippedwith the electric motor according to claim 1, wherein both sides of theinput shaft are supported by the counter output shaft, on an innercircumferential side of a supporting portion to the drive unit case ofthe counter output shaft.
 4. The drive unit equipped with the electricmotor according to claim 1, wherein a case body and a front cover of thecase body support the counter output shaft to the drive unit case,through radial ball bearings.
 5. The drive unit equipped with theelectric motor according to claim 1, wherein the counter output shafthas a counter drive gear which is integrated therewith.
 6. The driveunit equipped with the electric motor according to claim 1, wherein theplanetary gear set is provided such that the element which is connectedto the input shaft is drive-connected to an oil pump, on another side ofthe planetary gear set.
 7. The drive unit equipped with the electricmotor according to claim 1, wherein the counter output shaft isconnected to a wheel through a gear train, and a second electric motoris connected to the gear train.
 8. A drive unit equipped with anelectric motor, comprising: an input shaft that is connected to anengine; an electric motor shaft that serves as an output shaft of anelectric motor; a counter output shaft; a planetary gear set fordrive-connecting the input shaft, the electric motor shaft and thecounter output shaft so as to enable mutual transmission of power inwhich the input shaft is arranged in a coaxial relationship in an innercircumference of the counter output shaft; and a case body, wherein anouter circumference of both edge portions of the counter output shaft issupported by a front cover and an intermediate wall of the case body andan outer circumference of the input shaft is supported by an innercircumference of the counter output shaft by the case body through thecounter output shaft.
 9. The drive unit equipped with the electric motoraccording to claim 8, wherein a supporting portion of the input shaft isplaced at a same position as a supporting portion of the counter outputshaft, in an axial direction.
 10. The drive unit equipped with theelectric motor according to claim 8, wherein both sides of the inputshaft are supported by the counter output shaft, on an innercircumferential side of a supporting portion to the case body of thecounter output shaft.
 11. The drive unit equipped with the electricmotor according to claim 8, wherein the counter output shaft has acounter drive gear which is integrated therewith.
 12. The drive unitequipped with the electric motor according to claim 8, wherein theplanetary gear set is provided such that the element which is connectedto the input shaft is drive-connected to an oil pump, on another side ofthe planetary gear set.
 13. The drive unit equipped with the electricmotor according to claim 8, wherein the counter output shaft isconnected to a wheel through a gear train, and a second electric motoris connected to the gear train.